Hack attack leaves 1,400 airline passengers grounded

Ten planes and around 1,400 passengers of Polish airliner LOT were grounded Sunday after a major hacking attack jammed the carrier's systems, the company confirmed.

LOT's computer system suffered an attack on Sunday afternoon which left it unable to send flight plans to the aircraft before takeoff. Without this document—which details the route, weather and other important information—the planes were not able to fly, LOT spokesperson Adrian Kubicki told CNBC by phone.

The issue, which took five hours to solve, meant that 10 flights were cancelled and around 15 were delayed at Warsaw Chopin airport.

Kubicki said the hackers carried out a so-called distributed denial of service (DDoS) attack which overwhelms a network with traffic, but the motive was unclear.

Bartek Sadowski | Bloomberg | Getty Images

"We cannot judge or guess what the motivation was because at this stage," Kubicki said.

The passengers affected either flew on later flights or put up in hotels by LOT. Kubicki said that planes in the air were not affected and now user data was compromised.

LOT is now investigating the incident and will send the details to law enforcement agencies. Kubicki said he was concerned because the system used by LOT is the same as other airlines and they could be open to the same attack.

Planes have become increasingly connected to the Internet, raising many concerns about potential hacking threats. A report by the U.S. Government Accountability Office this year highlighted the ability for whole plane systems to be compromised if in-flight Wi-Fi is hacked.

"This story highlights the fact that, as more and more aspects of our lives become cyber-dependent, we offer a greater attack surface to cybercriminals – including critical infrastructure systems," David Emm, principal security researcher at Kaspersky Lab told CNBC via email.